JPH117667A - Device and method for recording/reproducing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method for recording/reproducing, which are capable of always reproducing recorded information under an optimal reproducing condition by determining the state of a probe tip and feedback-controlling the reproducing condition according to the state of the probe tip. SOLUTION: A recording/reproducing device or method is constructed in such a manner that a probe 1 arranged close to and oppositely to the surface of a recording medium 3 is run on the surface of the same for scanning, the state change of the recording medium 3 is caused by the probe 1 so as to record information and the state change recorded in the recording medium 3 is detected by the reproducing scanning of the probe 1. During the reproducing scanning of the probe 1, the state of the probe tip is determined based on a signal detected in a recording dot part by the probe 1 and, based on the determined state of the probe tip, a reproducing condition is feedback-controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing apparatus and a recording / reproducing method. It relates to a control means for optimizing.

[0002]

2. Description of the Related Art A scanning tunneling microscope (hereinafter referred to as S) capable of observing a sample surface at an atomic scale spatial resolution.
Scanning probe microscope (hereinafter abbreviated as SPM) such as TM or a scanning atomic force microscope (hereinafter abbreviated as AFM)
Is being developed. The STM detects a tunnel current flowing when a distance between a probe and a sample is reduced to several nm or less, and forms a surface image including a distribution of electronic states. Also, A
The FM detects an atomic force acting between the probe and the surface of the sample when the probe held by the elastic body is brought close to the sample by several nm or less, and forms a surface image including unevenness information. further,
A multifunction peripheral in which a new function is added to SPM has been developed.
For example, the AFM / STM is based on the AFM configuration, and a voltage is applied to the sample by making the probe conductive so that a conductive distribution image can be obtained simultaneously with the unevenness of the sample surface (Japanese Patent Laid-Open No. -277903). In addition, a function to measure the microscopic magnetic distribution on the sample surface using a magnetic material for the probe and a function to measure the capacitance distribution on the sample surface using the probe as a capacitance sensor were combined. Equipment has been developed.

[0003] If these SPMs are applied, an ultra-high-density recording / reproducing apparatus capable of writing recording information in a local area of several tens nm or less can be constructed. For example, A
As an application of FM / STM, there is a recording / reproducing apparatus in which a recording dot is formed by changing the physical state of the recording medium locally by applying a voltage by applying a voltage on the recording medium as a probe. As an example, a recording dot is formed by applying a voltage to the recording medium during recording and changing the conductivity of the recording medium, and a weak voltage is applied during reproduction to detect the change in conductivity. Recording / reproducing device (J. Vac. Sc)
i. Technol. B14 (2) 1353, Mar /
Apr 1996). In the above recording / reproducing apparatus, at the time of recording / reproducing for recording / reproducing using the change in the conductivity of the recording medium, a constant voltage is applied to the probe, a current flowing through the recording medium is detected, and the probe has higher conductivity than surroundings. A method of recognizing a portion as a recording dot and reproducing information is used.
Alternatively, a method of detecting the rate of change of the current and recognizing it as a recording dot when there is a portion having higher conductivity than the surroundings may be used.

[0004]

In the recording / reproducing apparatus to which the scanning probe microscope is applied, the physical quantity detected by the probe is significantly affected by the state of the tip of the probe. In the recording / reproducing apparatus, the state of the tip of the probe may change due to non-conductive dust on the recording medium adhering to the tip of the probe during scanning. In a recording / reproducing apparatus that performs recording and reproduction using the same probe, when a recording operation such as application of a voltage is performed on a defective portion of a recording medium,
The state of the tip of the probe may change due to a change in the radius of curvature of the tip or the attachment of a part of the recording medium to the probe. The current flowing through an insulating material is dominated by the tunnel current, and the tunnel current exhibits an exponential distance dependence.Therefore, if there is an insulating substance at the tip of the probe, the current flowing through the probe will be It becomes sensitive to the thickness and physical properties of the deposit.

Therefore, in a recording / reproducing apparatus that performs recording by using the change in conductivity of a recording medium, when an insulating substance adheres to the tip of the probe, the effective voltage applied to the recording medium decreases, and the probe becomes There is a problem that the detected current signal is significantly reduced. At this time, when a system that recognizes that a recording dot is formed when the detected current is higher than the threshold current value is used, there is a problem that the recording dot cannot be recognized due to a decrease in current level. . Alternatively, when the reproduced signal is remarkably increased and a signal exceeding the appropriate range is detected, or when the noise level is increased, a good S / N cannot be obtained and the reproduction becomes difficult. there were. A similar problem exists in the case of a recording / reproducing apparatus that performs recording with a change in capacitance. Since the capacitance decreases in inverse proportion to the distance between the probe and the recording medium, it is sensitive to changes in the tip of the probe. There is a problem that the detection sensitivity is reduced even when the material slightly adheres. Also, in a magnetic recording type recording / reproducing device, since the magnetic force decreases in proportion to the cube of the distance, it is sensitively affected by the state of the tip of the probe. There is a problem that the detection signal intensity is reduced when is attached.

Accordingly, the present invention solves the above-mentioned problems in the prior art, judges the state of the tip of the probe, performs feedback control of the reproduction condition in accordance with the state of the tip of the probe, and always records under the optimum reproduction condition. It is an object of the present invention to provide a recording / reproducing apparatus and a recording / reproducing method capable of reproducing information.

[0007]

In order to solve the above-mentioned problems, the present invention is characterized in that a recording / reproducing apparatus and a recording / reproducing method are configured as follows. That is,
The recording / reproducing apparatus of the present invention records information by causing a probe arranged in proximity to and facing the surface of a recording medium to scan the surface of the recording medium and causing the probe to change the state of the recording medium. A recording / reproducing apparatus for detecting a state change recorded on the recording medium by reproducing scanning of the probe, wherein the reproducing probe scans the probe based on a signal detected at a recording dot portion during the reproducing scanning of the probe. It is characterized by having a probe tip evaluation mechanism for judging the state of the probe tip, and a reproduction condition control mechanism for feedback-controlling the reproduction condition based on the judgment result of the probe tip evaluation mechanism. Further, the recording / reproducing apparatus of the present invention is characterized in that the determination of the state of the tip of the probe includes a detection signal detected by a current detection circuit,
It is characterized by comparison with a preset reference signal. Further, the recording / reproducing apparatus of the present invention is characterized in that the comparison of the signals is performed based on a time average of the detection signals. Further, the recording / reproducing apparatus according to the present invention is characterized in that the detection signal is a current signal flowing through a recording dot portion or a capacitance at the recording dot portion. Further, the recording / reproducing apparatus of the present invention is characterized in that the reproduction condition under feedback control is a voltage condition applied to the recording medium or a contact force when the probe is brought into contact with the recording medium. Further, in the recording / reproducing method of the present invention, the probe arranged close to and opposed to the surface of the recording medium is caused to scan the surface of the recording medium, and the state of the recording medium is changed by the probe. And a state change recorded on the recording medium is detected by a reproduction scan of the probe, and a signal detected by the probe at a recording dot portion during the reproduction scan of the probe is provided. The condition of the tip of the probe is evaluated based on the condition, and the reproduction condition is feedback-controlled based on the evaluated condition of the tip of the probe. Further, the recording / reproducing method of the present invention is characterized in that the evaluation of the state of the tip of the probe is based on a comparison between a detection signal detected by a current detection circuit and a preset reference signal. In the recording / reproducing method according to the present invention, the comparison is performed based on a time average of the detection signal. Further, the recording / reproducing method according to the present invention is characterized in that the detection signal is a current signal flowing through a recording dot portion or a capacitance at the recording dot portion. Further, the recording / reproducing method of the present invention is characterized in that the reproducing condition is a voltage condition applied to the recording medium or a contact force when the probe is brought into contact with the recording medium.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, according to the present invention, a probe arranged close to a surface of a recording medium is caused to scan the surface of the recording medium, and the recording is performed using the probe. The present invention is applied to a recording / reproducing apparatus that records information by causing a change in the state of a medium and that reproduces information by detecting a change in the state of the recording medium using the probe. During scanning, the reproduction condition is feedback-controlled based on the signal detected by the probe at the recording dot portion, thereby maintaining the optimum reproduction condition reflecting the state of the tip of the probe and stabilizing the reproduction signal intensity. Signals from individual recording dots may be distributed around a standard value having a certain signal intensity and signal detection time depending on the recording state.
In this case, if the reproduction condition is feedback-controlled based on the signal from the recording dot detected immediately before, the optimum condition for the next recording dot may not always be obtained. Further, the fluctuation of the reproduction condition becomes large and the reproduction becomes unstable. In such a case, a time average of detection signals from a plurality of continuous recording dots detected immediately before a recording dot providing a reproduction condition is obtained, and the reproduction condition is feedback-controlled based on the result. As a result, the distribution of the recording state of the recording dots is averaged, and the change in the probe tip as an average can be reflected in the feedback control without depending on a sudden event, and smooth control can be performed. Will be able to In particular, in a recording / reproducing apparatus that performs recording / reproduction using a change in conductivity of a recording medium, a signal serving as a basis for performing feedback control can be a current flowing through a recording dot.

[0009] The current flowing through the recording dot changes sensitively with respect to the voltage applied to the recording dot portion, and if there is an insulating substance at the tip of the probe, the effective voltage applied to the recording dot portion decreases. As a result, the reproduction current signal at the recording dot portion decreases. At this time, in order to increase the current signal, it is necessary to increase the voltage applied to the tip of the probe. Therefore, the signal from the recording dot can be stabilized by taking the current flowing through the recording dot as the signal and taking the voltage applied to the probe and the substrate electrode as the reproduction condition for the feedback control. Also, in a recording / reproducing apparatus that performs recording / reproducing using a change in the capacitance of a recording medium, when a signal is detected by applying a voltage to a probe at the time of reproducing to detect a capacitance, output is performed by an applied voltage. The signal changes sensitively. Therefore, in this case, the reproduction conditions that are feedback-controlled based on the detection signal that is the capacity of the recording dot portion include:
The detection signal at the recording dot portion can be stabilized by setting the voltage condition applied to the recording medium. In addition, when the recording medium is made of an elastically deformable material, by increasing the contact force of the probe with the sample,
The contact area between the probe and the recording material can be increased,
As a result, the reproduced signal can be increased. When the radius of curvature at the tip of the probe changes, the detection signal decreases. However, the detection signal can be increased by increasing the contact force and increasing the contact area. Therefore, in this case, by taking the contact force at the time of bringing the probe into contact with the recording medium as the reproduction condition to be feedback-controlled, the adhesion of the probe to the recording medium can be controlled,
The signal detected by the probe can be kept at a constant level.

[0010]

Embodiments of the present invention will be described below. [Embodiment 1] FIG. 1 shows the configuration of a recording / reproducing apparatus according to Embodiment 1 of the present invention. A probe for forming and detecting a recording dot includes a probe 1 and a cantilever 2. Cantilever 2 and probe 1 held at one end
Was formed integrally with Si. The cantilever is a thin film and has properties as a spring. The probe 1 and the cantilever 2 have a surface thickness of about 500 in order to have high conductivity.
nm of Pt. The spring constant of the cantilever was about 0.01 N / m, and the radius of curvature at the tip of the probe was 100 nm or less. The cantilever 2 was fixed to the main body so that the probe 1 faced the recording medium. Substrate 4 on which recording medium 3 is loaded
Was fixed to the holder 5. Substrate 4 on which recording medium 3 is loaded
Is conductive and is one electrode for applying a voltage to the recording medium 3. The bottom of the holder 5 was fixed to a displacement mechanism 6. The displacement mechanism 6 was fixed to the main body via the coarse movement mechanism 7.
The displacement mechanism 6 is composed of a cylindrical piezoelectric element, is driven by a displacement element drive circuit 12, and can precisely displace the substrate in directions parallel and perpendicular to the substrate surface. By displacing the displacement mechanism 6 in XY and the recording medium 3 fixed thereto in XY displacement, the probe 1 can be relatively scanned with respect to the recording medium 3. The coarse movement mechanism 6 drives the recording medium 3 to approach the probe 1.

The recording medium 3 used in this embodiment is disclosed in
It is a polyimide thin film which is a cumulative film of an organic compound having a memory effect on switching of current-voltage characteristics as disclosed in JP-A-3-161553. For example, by applying a voltage of several volts to the polyimide thin film for a period of several tens of μs or less, the electrical conduction characteristic can be changed from a high resistance state to a low resistance state. When a voltage is applied to the recording medium using a probe having a radius of curvature of several tens of nm, the conductivity of the recording medium is locally changed, and recording dots having a size of about 10 nm can be formed. The substrate 4 is formed by depositing about 5 nm of Ti on a quartz glass substrate by a vacuum evaporation method, and then forming Au on the quartz glass substrate by the same method.
Was used to have a thickness of 30 nm. On this board, LB
Polyamide acid was accumulated in 10 layers by the method, and then heat-treated to form a polyimide thin film, thereby obtaining a recording medium. The thickness of the polyimide thin film was about 5 nm.

The control unit 11 is a part that controls the operations of scanning the probe and detecting the signal in a coordinated manner. The controller 11 controls the scanning and recording of the probe during recording, and detects the position of the probe during reproduction. And has a function of performing reproduction by associating the reproduced signals. First, the operation at the time of recording will be described. The control unit 11 drives the coarse movement mechanism 7 with respect to the displacement mechanism drive circuit 12 to bring the recording medium 3 into contact with the probe 1. Next, the displacement mechanism 6 is driven to cause the probe 1 to scan relative to the recording medium 3. Here, the recording points are set in a grid,
The probe performs raster scanning so as to connect the lattice points. When the probe 1 reaches the recording point, the control unit 11 synchronously issues a command to the voltage application mechanism 8 to apply a recording pulse voltage between the probe 1 and the substrate, and performs recording. . The recording pulse voltage has a peak value of 10 V and a width of 1 μm.
s square wave. When voltage is applied under these conditions,
It is observed that a current having a maximum current value of 1 μA or more flows, and recording dots are formed. FIG. 3 shows the relationship between the applied voltage and the current flowing through the recording dot portion of the recording medium used in this embodiment before and after the formation of the recording dots.
The dotted line represents the regeneration voltage, as will be shown later. In the region of a voltage of several volts near the reproduction bias, the current has a monotonically increasing relationship with the voltage increase both before and after recording dot formation. The relationship between the voltage and the current is non-linear, and has a property that the current sharply increases as the voltage increases.

Next, a method of reproducing recorded information will be described. As described above, the recorded information is recorded as a local change in conductivity of the recording medium, and the information is reproduced by detecting the change in conductivity. The control unit 11 drives the coarse movement mechanism 7 to bring the probe 1 into contact with the recording medium 3. Next, the control unit 11 causes the voltage application mechanism 8 to apply a DC voltage between the probe 1 and the substrate. Alternatively, a method of detecting a change in resistance value by applying an AC voltage and performing phase detection of a detection current can be adopted. The control unit 11 drives the displacement mechanism 6 to cause the displacement mechanism drive circuit 12 to scan the probe 1. The current flowing through the probe 1 is a current detection circuit 9
After being converted into a voltage and amplified, it is sent to the control unit 11 as a signal. The control unit 11 compares the signal with the probe position, constructs an arrangement pattern of recording dots on the recording medium 3, and reproduces information. Here, construction of an array of recording dots will be described. As shown in FIG. 2, when the probe 1 scans over the recording dot row, a current signal is detected. In FIG. 2, the horizontal axis represents the time axis. The time axis is represented so as to correspond to the position coordinates in the scanning direction using the scanning speed as an intermediate parameter. In the scanning direction, only the signal of the portion where the current value higher than before and after is detected. Further, the peak intensity of the signal of the recording dot portion is detected,
This peak signal intensity is compared with a reference value, and if it is higher than a threshold value, it is recognized as an ON bit. Alternatively, it is also possible to use a method of taking a derivative of the current signal as a signal and extracting a signal only in a portion where the signal exceeds a certain threshold. According to this method, a strong signal can be obtained even when the detection current is small. Also, by taking the differential value, the low frequency change of the current value is removed,
It has the advantage that gradual changes in the background can be eliminated. However, when there is much noise, it may be difficult to distinguish between a signal and noise.

Next, detection of the state of the probe tip will be described. The ON bit signal detected by the current detection circuit 9 is input to the probe tip state evaluation mechanism 10. A reference signal is set in advance in the probe tip state evaluation mechanism 10 according to a table included therein. In the probe tip state evaluation mechanism 10, O
The peak intensity of the N-bit signal is compared with the reference signal and ON
The shift amount between the bit signal and the reference signal value is obtained. If the current value is smaller than the reference value, it is determined that the state of the tip of the probe is in a state where current detection is difficult. In such a case, when a low conductive substance adheres to the tip of the probe, or
There may be a case where there is an adhering substance not at the tip of the probe but around the probe and a gap is formed between the probe and the recording medium.
When a larger amount of current flows than the reference value, it is determined that the state of the tip of the probe is in a normal state in which the current easily flows. As such a case, the tip of the probe is very clean, or the radius of curvature of the tip of the probe has changed from the initial one. However, when the current detection circuit 9 in the present embodiment detects a current of 1 μA or less, the output is saturated.
It is desirable to keep it below. In addition, in the state of the probe tip where the current can be easily detected, the noise level (usually a value lower than the signal from the recording dot) increases, so that the S / N of signal detection decreases. Therefore, in order to perform appropriate reproduction, it is necessary to lower the reproduction bias to lower the current level. By the way, when the state of the tip of the probe is determined from the signal at each recording point, if there is a variation in conductivity depending on the recording state of each recording point,
It is not always possible to determine an appropriate state by only a signal from one recording point. Therefore, in order to more accurately determine the state of the tip of the probe, a recording point to be reproduced is turned on with respect to a signal corresponding to 20 recording points before the recording point.
For only the bit signal, determine the average value of the peak intensity of the signal, compare this average value with the reference value, determine the deviation amount of the average value from the reference value, and judge the tip state of the probe from the deviation amount. did. By performing this process, the influence of variations in conductivity on individual recording dots can be reduced, and changes in the state of the probe can be accurately extracted.

In this embodiment, in addition to the above-mentioned reproducing mechanism,
A reproduction condition control mechanism 13 for determining a reproduction condition according to the state of the probe tip performed by the probe tip evaluation mechanism 10 and performing feedback control of the reproduction condition is added. Here, the playback conditions are
This is a bias voltage condition. Probe tip condition evaluation mechanism 10
Determines an appropriate reproduction condition from the tip state of the probe, and transmits the reproduction condition to the reproduction condition control mechanism 13. The reproduction condition control mechanism 13 controls the voltage application mechanism 8 based on the reproduction conditions.
And the feedback control of the reproduction bias voltage is performed. In the control of the regeneration conditions, near the reference current value,
The voltage and current in FIG. 3 are regarded as having a substantially linear relationship, and the voltage is feedback-controlled by an amount proportional to the amount of deviation. That is, if the current signal becomes smaller than the reference value,
Increase the reproduction bias in proportion to the amount of deviation,
When the current signal becomes larger than the reference value, a control for reducing the reproduction bias in proportion to the amount of deviation is performed. Here, １1 nA was set as the reference current.
From FIG. 3, since this current value is obtained at 2 V,
The initial voltage was set at 2V.

As described above, by detecting the change in the current value in the recording dot portion detected by the probe and performing feedback control of the applied bias voltage, it is possible to perform reproduction with an appropriate reproduction bias voltage. It has become possible to perform stable reproduction. Further, in the present embodiment, the recording dots are detected by the change in the current flowing through the recording medium. However, even when the reproduction is performed by the method of detecting the change in the capacitance of the recording medium, the reproduction signal is obtained by performing the same control. Can be stabilized. In the case of performing signal detection by applying a voltage to the probe at the time of reproduction and performing capacitance detection, the output signal changes sensitively according to the applied voltage. Therefore, the voltage applied to the recording medium by the probe is set as the reproduction condition. If the applied voltage is feedback-controlled based on the detection signal, which is the capacitance at the recording dot portion, the detection signal at the recording dot portion can be stabilized.

[Embodiment 2] In this embodiment, the contact force of the probe is controlled based on the signal from the recording dot detected by the probe. FIG. 4 shows a configuration diagram of a recording / reproducing apparatus according to the second embodiment.
The reproducing apparatus according to the present embodiment is different from the reproducing apparatus according to the first embodiment in that a mechanism for detecting the displacement of the cantilever 2 for detecting the contact force of the probe is added. Example 1
Those having the same functions as those described above are represented by the same numbers.
First, displacement detection will be described. For detecting the displacement of the cantilever 2, an optical leverage method using a laser beam was used. This is a method of irradiating the back surface of the cantilever 2 with a laser beam and measuring the deviation of the reflection angle of the reflected light. That is, the laser light emitting element 15 and the laser light receiving element 16 are fixed to the main body, and the laser light emitted from the laser light emitting element 15 irradiates near the free end of the cantilever 2 holding the probe 1, and the reflected light is irradiated with the laser light. The light was incident on the element 16. As the laser light receiving element 16, a four-division sensor composed of a photodiode was used. By comparing the intensity of light received by each sensor, it is possible to detect the deflection of the cantilever 2 in the Z direction and the twist from the horizontal plane. When the probe 1 receives a force due to the interaction with the recording medium 3, the cantilever 2 which is an elastic body is displaced in accordance with the force received by the probe 1, and at the same time, the reflection angle of the reflected laser light is deviated. The signal detected by the laser light receiving element 16 is sent to the displacement detection mechanism 15 and measures the displacement of the cantilever 2.

FIG. 4 shows the relationship between the cantilever base-medium distance and the force applied to the probe at that time when the probe is in contact with the recording medium. When the base of the cantilever 2 approaches the recording medium, the pressing force of the probe against the recording medium increases. In a range where the displacement of the probe 1 is small and the deflection of the cantilever 2 is small, the contact force of the probe and the distance between the cantilever and the medium have a linear relationship. Therefore, the contact force of the probe 1 can be detected from the inclination of the curve and the position of the base of the cantilever 2. The recording medium and the formation of the recording dots and the detection of the recording dots used in this embodiment are the same as those in the first embodiment. The recording dot is formed as a change in conductivity in a minute area on the recording medium, and the detection of the recording dot is performed by a current flowing through the recording dot. FIG. 5 is a diagram showing the relationship between the contact force of the probe with the recording medium and the current flowing through the probe when the voltage applied to the recording dot portion is constant. As shown by the solid line in the figure, the current flowing through the probe increases as the contact force increases. It is considered that this is because, when the contact force is increased, the recording medium in the portion where the probe contacts is slightly deformed, and the area where the probe contacts the recording medium is increased. When the state of the tip of the probe changes, the linear relationship in FIG. 5 shifts, and even with the same contact force, the current flowing through the probe differs from that before the change of the tip. However, the monotonically increasing relationship between the contact force of the probe and the current value is maintained. Using the above relationship, it can be seen that in order to keep the current signal from the recording dot detected by the probe constant, the contact force of the probe should be feedback-controlled according to the state of the tip of the probe.

Next, the reproducing operation will be described. First,
The control unit 11 issues a command to the displacement mechanism drive circuit 12 to drive the coarse movement mechanism 7 so that the probe 1 approaches the recording medium 3. Next, the displacement mechanism drive circuit 12 Z-drives the displacement mechanism 7 to bring the probe 1 into contact with the recording medium 3. The contact at this time is determined from the displacement of the cantilever detected by the displacement detection mechanism 15. Next, the control unit 11 issues a driving command to the displacement mechanism driving circuit 12, and the displacement mechanism driving circuit 12 drives the displacement mechanism 6 to displace the substrate horizontally on the plane of the substrate 4 to record dots on the recording medium 3. The probe 1 is caused to scan along the row. A constant bias voltage (2 V) is applied between the probe 1 and the substrate 4 by a voltage applying mechanism 8.
A current signal flowing through the probe 1 is detected by a current detection circuit 9. Further, the current signal is sent to the probe state evaluation mechanism 10 and the control unit 11. In the control unit 11, the current detection circuit 9
The signal from is made to correspond to the position where the signal is detected, an array pattern of recording dots is constructed, and information is reproduced. On the other hand, the probe state evaluation mechanism 10 compares the value of the current signal sent from the current detection circuit 9 with the reference current value, detects a deviation amount from the reference current value, and detects the deviation amount of the probe tip from the deviation amount. The state was determined. At this time, the method of evaluating the state of the tip of the probe conforms to the method described in the first embodiment. Further, the state of the probe tip is transmitted to the reproduction condition control mechanism 13,
The reproduction condition control mechanism 13 determines an appropriate reproduction condition based on the state of the probe tip.

Next, control of reproduction conditions will be described.
As described above, in the present embodiment, the controlled reproduction condition is the contact force of the probe, and this contact force is the displacement detection mechanism 1.
5 is the quantity to be measured. In order to change the contact force of the probe, the displacement mechanism drive circuit 12 drives the displacement mechanism 6 to change the distance between the recording medium 3 and the holding portion of the cantilever 2. Here, it is necessary that the reference value of the contact force of the probe be such that the current signal is within the detection range of the current detection circuit. Further, the contact force of the probe needs to be set small enough not to break the recording medium or the tip of the probe. In this embodiment,
Since the displacement mechanism 6 is composed of a piezoelectric element, the voltage for displacing the displacement mechanism 6 in a direction perpendicular to the surface of the recording medium 3 was changed in order to change the contact force of the probe with the recording medium. . That is, if the signal intensity shifts in the direction in which the peak intensity of the signal from the recording dot decreases, the reproduction condition control mechanism 13 drives the displacement mechanism drive circuit 12 to increase the contact force of the probe. In the meantime, the distance between the base of the cantilever 2 and the recording medium 3 is shortened. On the other hand, if there is a deviation in the direction in which the peak intensity of the signal from the recording dot increases, the contact force of the probe is reduced. The displacement mechanism is driven in a direction in which the distance between the base of the recording medium 3 and the recording medium 3 is increased. As described above, the current signal can be stably detected by feedback-controlling the contact strength of the probe according to the signal strength to be detected.

[0021]

As described above, according to the present invention, at the time of reproducing scanning of the probe, the state of the tip of the probe due to the adhering matter or the like is determined based on the signal detected by the probe at the recording dot portion. Since the reproducing condition is feedback-controlled based on the state of the needle tip, it is possible to always detect the recording dot under the optimum reproducing condition, and to stably reproduce the information recorded on the recording medium. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a recording and reproducing device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a detection signal when a recording dot row is scanned.

FIG. 3 is a diagram showing voltage-current characteristics before and after recording on a recording medium.

FIG. 4 is a configuration diagram of a recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the distance between the probe base and the recording medium and the contact force of the probe.

FIG. 6 is a diagram illustrating a relationship between a contact force of a probe and a detection current.

[Explanation of symbols]

 1: probe 2: cantilever 3: recording medium 4: substrate 5: holder 6: displacement mechanism 7: coarse movement mechanism 15: laser light emitting element 16: laser light receiving element

Claims (10)

[Claims] A probe, which is disposed in close proximity to the surface of a recording medium, scans the surface of the recording medium, and changes the state of the recording medium with the probe to record information. What is claimed is: 1. A recording / reproducing apparatus for detecting a state change recorded on a recording medium by reproducing scanning of said probe, wherein said reproducing tip scans said probe based on a signal detected at a recording dot portion by said probe. 1. A recording and reproducing apparatus comprising: a probe tip evaluation mechanism for judging a state of the probe tip; and a reproduction condition control mechanism for feedback-controlling a reproduction condition based on a judgment result of the probe tip evaluation mechanism. 2. The recording / reproducing apparatus according to claim 1, wherein the determination of the state of the tip of the probe is made by comparing a detection signal detected by a current detection circuit with a preset reference signal. 3. The recording / reproducing apparatus according to claim 2, wherein the comparison of the signals is performed based on a time average of the detection signals. 4. The recording / reproducing apparatus according to claim 1, wherein the detection signal is a current signal flowing through a recording dot portion or an electrostatic capacitance at the recording dot portion. . 5. The reproducing condition according to claim 1, wherein the reproducing condition under feedback control is a voltage condition applied to the recording medium or a contact force when the probe is brought into contact with the recording medium. A recording / reproducing apparatus according to any one of the preceding claims. 6. A method in which a probe arranged close to and opposed to the surface of a recording medium is caused to scan the surface of the recording medium, and the state of the recording medium is changed by the probe to record information. What is claimed is: 1. A recording / reproducing method for detecting a state change recorded on a recording medium by reproducing scanning of said probe, wherein said reproducing probe scans said probe based on a signal detected at a recording dot portion during reproducing scanning of said probe. A recording / reproducing method comprising: evaluating a state of a tip and performing feedback control of a reproducing condition based on the evaluated state of the tip. 7. The recording / reproducing method according to claim 6, wherein the evaluation of the state of the tip of the probe is based on a comparison between a detection signal detected by a current detection circuit and a preset reference signal. 8. The recording / reproducing method according to claim 7, wherein the comparison is performed based on a time average of the detection signal. 9. The recording / reproducing method according to claim 6, wherein the detection signal is a current signal flowing through a recording dot portion or a capacitance at the recording dot portion. . 10. The recording medium according to claim 6, wherein the reproduction condition is a voltage condition applied to the recording medium or a contact force when the probe is brought into contact with the recording medium. Recording / reproducing method described in 1.